US4350771A
Expired / Lapsed
US
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Oxidation resistant silicon nitride containing rare earth oxide
Assignee: Verizon Laboratories Inc
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Filing: 1981-09-18
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Granted: 1982-09-21
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Expires: 2001-09-18
Abstract
Abstract Si 3 N 4 polycrystalline ceramic bodies formed from starting materials containing about 2 to 4 weight percent SiO 2 , less than 0.1 weight percent cation impurities and Y 2 O 3 in critical amounts exhibit optimum oxidation resistance. Such bodies are useful as engine parts or components or as regenerator structures for waste heat recovery.
Inventors
- 👤 J. Thomas Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:59
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
109 words
A polycrystalline ceramic body consisting essentially of a composition of Si 3 N 4 , SiO 2 and Y 2 O 3 , said composition lying within a triangular region of the Si 3 N 4 -SiO 2 -Y 2 O 3 ternary composition diagram bounded by lines joining the points Si 3 N 4 , Y 2 O 3 .2SiO 2 , 10Y 2 O 3 .9SiO 2 .Si 3 N 4 , and Si 3 N 4 .Y 2 O 3 , said compositions having from about 2 to about 4 weight percent SiO 2 and up to about 13 weight percent Y 2 O 3 .
Claim 2
Dependent Claim
109 words
A polycrystalline ceramic body consisting essentially of a composition of Si 3 N 4 , SiO 2 and Y 2 O 3 , said composition lying within a triangular region of the Si 3 N 4 -SiO 2 -Y 2 O 3 ternary composition diagram bounded by lines joining the points Si 3 N 4 , Y 2 O 3 .2SiO 2 , 10Y 2 O 3 .9SiO 2 .Si 3 N 4 , and Si 3 N 4 .Y 2 O 3 , said compositions having from about 2 to about 4 weight percent SiO 2 and up to about 13 weight percent Y 2 O 3 .
Claim 3
Dependent Claim
22 words
The body of claim 1 wherein Y 2 O 3 is present in the amount of about 11 to 13 weight percent.
Claim 4
Dependent Claim
19 words
The body of claim 2 wherein SiO 2 is present in the amount of at least 3 weight percent.
Claim 5
Dependent Claim
13 words
The body of claim 1 wherein cation impurities are below 0.1 weight percent.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-20 | 1986-03-22 | 1986-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-20 | 1990-03-22 | 1990-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-20 | 1994-03-22 | 1994-09-21 | $7700.00 | Window Closed / Lapsed |